“Else when thou shalt bless with the spirit, how shall he that occupieth the room of the unlearned say Amen at thy giving of thanks, seeing he understandeth not what thou sayest?”
King James Version (KJV)
14:16 Otherwise how shall he that filleth the place of a private person - That is, any private hearer. Say Amen - Assenting and confirming your words, as it was even then usual for the whole congregation to do.
1Co 14:16 Else when thou shalt bless with the spirit, etc. If an unknown tongue is used, how can one who does not understand it "say Amen" to the blessing at the proper place? The unlearned. A private person, the private members of the church, those not possessed of the spiritual gifts. Say Amen. This shows that audible responses to the praises and thanksgivings were the custom of the church.